122 (#176) ############################################ WOOLLEN AND WORSTED SPINNING Diameter Reciprocal of Condensed Sliver Fibre Length (3•1416) = Cot. of angle (for one coil of fibre round the thread). 3a. To find the turns of spindles to be inserted during the outward movement of the carriage : Reciprocal of Yarn Diameter x Inches Traverse of Carriage Cot. of angle required for drafting x + (3.1416) Turns of spindles during outward traverse of carriage. 4. To find the retardation of the carriage to maintain the required drafting-twist angle : (P1) Ví x seconds for completion of outward draw (P) x ✓N seconds required to complete the 1st period. (P2) vã x seconds for completion of outward draw (Pn) VN seconds required to complete the 1st and 2nd periods (Pn) VN x seconds for completion of outward draw (P7) VN seconds required to complete the Nths periods. The drawing-out scrolls should be designed, in con- junction with the driving gear, to give as nearly as possible the retardation given in these formulas. The drafted woollen thread will be twisted from, say, a 4° drafting twist angle to about a 25° twist angle- this being the usual angle of twist inserted in woollen yarns for maximum strength, although it should obviously be varied according to the purpose in view. The two following formulas (strictly logical) will here prove useful :- D Cot. of Angle x 16 T (turns per i in.) and, D Cot. of Angle given by any turns per 1 in. TX TE 122